The aim of this paper is to provide the basis for the calibration of a hydrophone "in situ" with a non-omnidirectional source at 10 kHz, thus assigning a value of uncertainty, which may be high, but according to requirements, may be sufficient

The cascaded integrator-comb (CIC) filters are widely used as decimators in many applications, such as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a so-called least-squares filters (LSF) based on B-splines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the B-splines expanded by an integer factor. We show that the least-squares filters based on B-splines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anti-causal IIR filters needed to implement LSFs.

The cascaded integrator-comb (CIC) filters are widely used as decimators in many applications, such
as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a so-called least-squares filters (LSF) based on B-splines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the B-splines expanded by an integer factor. We show that the least-squares filters based on B-splines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anti-causal IIR filters needed to implement LSFs.

This study aims to estimate a model for the underwater acoustic environment in a Mediterranean area and to compare the model with existing other models of the sound attenuation in the zone of interest. The contribution of this paper is to develop a protocol to validate and adjust the offshore underwater attenuation models to a model of a Mediterranean area.

This study aims to estimate a model for the
underwater acoustic environment in a Mediterranean area and to
compare the model with existing other models of the sound
attenuation in the zone of interest. The contribution of this paper
is to develop a protocol to validate and adjust the offshore
underwater attenuation models to a model of a Mediterranean
area.

In this paper we talk about an acquisition system
for seismic data. The Ocean Bottom Seismometer (OBS) is
equipment designed to obtain the seismic marine data from the
seabed. The main part of this paper is based in an application
which controls the acquisition data of four measurement
channels. This system has been tested in lab, getting the
corresponding results.

This work verifies and validates the calibration in a marine geophone by
means of a hyperbaric chamber before and after the pressure underwater laboratory
test. The objective is to characterise the transfer function according to the
frequency of coupling between the geophone and the sediment. It is possible to observe
the geophone coupling variations through the sediment after the test inside
the water pressure at the equivalent of 200 metres depth.

This work verifies and validates the calibration in a marine geophone by
means of a hyperbaric chamber before and after the pressure underwater laboratory
test. The objective is to characterise the transfer function according to the
frequency of coupling between the geophone and the sediment. It is possible to observe
the geophone coupling variations through the sediment after the test inside
the water pressure at the equivalent of 200 metres depth.

A tracking system with RFID technology has
been developed to measure the activity and behaviour of
species in laboratory. It consists of different controllers
which handle different RFID antennas. The controllers send
the data received from its antennas to a host computer that
computes the tracking of the different individuals. The
system has a tracking resolution of centimetres and was
specifically designed to respond in hostile environments and
to allow an easy configuration and expansion.

We can obtain the performance of the marine
seismometer upon the sediment to know its coupling in the
bottom sea. This paper deals with the coupling parameters in
order to obtain the geophone response through the
frequency. The use of the shake table and vibration
calibrator allows to deduce the coupling transfer function
between the geophone and the sediment sea without using a
detailed model of interaction sensor/seabed.

The main purpose of this work is to propose a dynamical model for simulating the response of different metallic objects when impacted by another rigid body. In addition, a methodology for estimating the model parameters is presented and discussed. Results from real experiments shows that by assuming certain characteristics on impacting objects, the dynamic model can reproduce the transient dynamics during contact time.

Swath-bathymetry and acoustic-backscatter data from the southwest Iberian margin, which hosts the present-day boundary between the European and African plates, reveal the surficial expression of several fault structures <100 km offshore of Portugal. High-resolution and multichannel seismic reflection profiles collected perpendicular to these structures show folding and reverse faulting of the Quaternary units, suggesting present-day tectonic activity. Successive submarine-landslide deposits at the base of the scarps provide evidence of cyclic fault activity. The location and dimension of these newly identified structures agree with the modeled source suggested for the A.D. 1755 Lisbon earthquake and tsunami, possibly the most destructive event in western Europe during historical time. These fault escarpments and deformed seafloor sediments associated with a cluster of shallow seismicity suggest that these thrusts are active and may pose a significant earthquake and tsunami hazard to the coasts of Portugal, Spain, and Morocco.